The present invention relates to an Albada finder that is commonly used in a compact camera.
As shown in FIG. 8, a conventional Albada finder is provided with a negative objective lens 202 and a positive eyepiece lens 204. An image boundary frame 210 indicates an area of an object to be photographed, that will be exposed on a frame of film in the camera. The image boundary frame 210 is formed on the object-side surface 204a of the positive eyepiece lens 204. An image of the frame 210 is reflected by a total reflection portion 206 that is formed on a peripheral area of the eyepiece-side surface 202a of the negative objective lens 202.
A finder of an auto-focus camera requires a focusing frame to indicate a detecting area of an auto-focus device. The focusing frame is also formed on the object-side surface 204a of the eyepiece lens 204. However, the entire area of the eyepiece-side surface 202a of the objective lens 202, enclosed by the total reflection portion 206, is formed as a half-mirror in order to allow light to pass through from the object to the eyepiece lens 204, and to reflect the image of the focusing frame back to the eyepiece lens 204.
Since the entire eyepiece-side surface of the above-mentioned conventional Albada finder is a half-mirror, the intensity of the light transmitted therethrough is reduced by one half. This results in the image of the object viewed in the finder becoming dark, making it difficult to see.